Television and like apparatus



May 26, 1931. 1 BIAJRD 1,807,464

TELEVISION AND LIKE APPARATUS Filed Oct. 7, 1929 3 Sheets-Sheet l y 26, 1931- J. L. BAIRD 1,807,464 I TELEVI S ION I AND LIKE APPARATUS Filed 001:. 7. 1929 s Sheets-Sheet 2 y 26, 1931- J. 1.. BAIRD 1,807,464

TELEVISION AND LIKE APPARATUS Filed Oct. 7, 192 9 3 Sheets-Sheet 3 //Y VENTQH X M m,

Patented May 26, 1931 'UNITED STATES PATENT OFFICE,

7 JOHN LOGIE BAIRD, OF LONDON, ENGLAND, ASSIGNOR TO TELEVISION LIMITED,

LONDON, ENGLAND, A. BRITISH COMPANY Application filed October 7, 1929, Serial No. 397,984, and in Great Britain October 10, 1928. p

This invention is for improvements in or relating to television and like apparatus and has for itsobject to provide improved apparatus for use at the receiving station andthe transmitting station of a television system.

The invention is concerned more. particularly with systems using an exploring device consisting of a rotatable disc having a spirally arranged set of lenses on it whereby the picture is explored in a series of parallel bands. Hitherto it has been necessary to use a number of lenses equal to the number of lines in the complete picture and one of the objects of this invention is to provide means whereby the number of lenses can be considerably reduced. Where the word lens is used in this specification, it is to be understood that any light-transmitting device such as a lens, mirror or aperture may be employed. p

According to one feature of this invention, a television system has, in combination, an exploring device which provides a series of laterally-displaced images whereof the maximum displacement is a fraction of the width of the picture, a plurality of light-sensitive cells (or light-sources) spaced apart across the picture and each appropriated to one zone the width of which is equal to the said maxi-. mum displacement, andmeans for exposing the light-sensitive cells (or light-sources) successively during successive cycles of operation of the exploring device.

7 According to another feature of this invention, a television or like apparatus comprises an exploring device, a plurality of light-sensitive cells each arranged respectively to explore during one operation of the exploring device, one zone or band of the object of which an image is to be transmitted, and a shutter, or like device operating automatically to expose said cellsin turn to the action of the exploring device.

According to yet another feature of this invention, a television or like apparatus com prises an exploring device, a plurality of light-sources each arranged respectively to reconstitute during one operation of the exploring device one zone or band of the picture, and a shutter or like device operating automatically to obscure said light sources in turn.

Convenient forms of apparatus according to the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings.

Figure 1 shows the relative arrangement of an object, an exploring disc, a shutter device and a group of light-sensitive devices according to this invention.

t Figure 2 shows a shutter device in the form of a circular disc. z

Figure 3 shows a modified form of shutter. device.

Figure 4 shows a form ofshutter device wherein the shutter is operated by the action of an electromagnet.

Figure 5is a diagram illustrative of a method of exploration in which a series of thirty images produced by the lenses of a sixlens exploring disc is swept, during five rotations of said disc, over a series of five light sensitive devices, which devices are exposed successively, one during each rotation of the exploring disc, whereby the image field is explored in a series of thirty lines constituting five different zones each zone comprising six of said lines, and each appertaining, respectively, to one of said light-sensitive devices; and V Figure 6 shows an arrangement of electric circuits includinga commutator suitable for the operation of a shutter device of the kind shown in Figure 4.

Referring to Figure 1, the object 10 at the transmitting station is illuminated by a suitable source of light (not shown) Each lens of the spiral set of lenses 11 in the exploring disc 12 casts a complete image of the object onto the shutter 13, these images being laterally displaced in a usual manner, but the maximum displacement is only a fraction of the width of the picture, instead of being equal to the full width thereof as heretofore. A set of light-sensitive cells are situated behind the shutter, spaced apart a distance equal to the aforesaid maximum displacement so that each cell explores a zone, in a number of lines equal to the number of lenses 11. The action of the shutter is such as to expose successively one of the light-sensitive devices, 14, 15, 16, 17, 18 and only one, during each complete rotation of the exploring disc 12. The object is thus explored by zones, each zone containing as many lines as there are lenses 11 in the exploring disc 12. Thus if there are five light-sensitive devices and six lenses, the object or picture 10 will be explored in thirty lines.

The diagram of Figure 5 is illustrative of such a method of exploration, and indicates the five zones 50, 52, 54, 56, 58 which are explored, respectively, by the five light-sensitive devices 14, 15, 16, 17 and 18, it being understood that each of these zones is constituted by six lines of exploration (i. e. one line corresponding to each of the lenses 11), although for the sake of clearness the full number of these lines is shown only in connection with the zone 50. In operation, assuming that the light-sensitive device 14 alone is being exposed by the action of the shutter 13, and that an image of the area to be explored is cast upon the shutter by the first or leading lens of the spiral of lenses 11, then rotation of the lens-carrying disc 12 will cause the image to sweep over the shutter, resulting in the image being explored along the line 60 by the device 14. During continued rotation of the disc 12 the image cast upon the shutter by the scond lens will, owing to the spiral arrangement of the lenses, sweep over the shutter along a. path which is displaced laterally in relation to the path taken by the image formed by the first lens, so that the image due to the second lens will be explored by the device 14 along the line 62. In like manner, the images cast by the third, fourth, fifth and sixth lenses Will sweep over the shutter along paths so displaced laterally that each of these images will be explored by the device 14 along the lines 64, 66, 68, respectively.

The zone 50 having now been completely explored, the shutter 13 covers the device 14 and exposes the next adjacent device 15. A second rotation of the lens-carrying disc 12 now causes a second series of six images, one due to each lens, to be swept over the shutter, resulting in the zone 52 being explored by the device 15 along six lines, the first and last of which are indicated, respectively, at 74 and 76. In like manner, the zones 54, 56 and 58 are explored successively during the next three rotations of the lens-carrying disc 12, the zone 54 being explored by the device 16 and the zones 56 and 58 by the devices 17 and 18 respectively. Thus the whole area to be explored is covered by 30 lines of exploration during five rotations of a disc carrying six lenses.

Figure 2 illustrates a convenient form of shutter according to this invention. A disc 19 is provided with arcuate slots 20 which are 65 so arranged as to expose the light-sensitive devices 26, 27, 28, 29, 3O successively and for the same period of time. The axis of the disc is disposed between two of the lightsensitive devices, and this disc is geared to the exploring disc so that, for each revolution of the latter, it makes, in the arrangement illustrated, one fifth of a revolution, since there are five cells.

Figure 3 illustrates an alternative form of shutter with which all the light-sensitive devices 26, 27, 28, 29, 30 are 011 one side of the axis of the disc,

Figure 4 represents another convenient form of shutter according to this invention. Each of the light-sensitive devices 31, 32, 33, 34, 35 is normally covered by a small plate 21, of which only one is shown, carried by an arm 22 which is held in the obscuring position by a spring 23 and a stop 24. By means of any convenient form of commutator driven by the exploring disc, an electric current is sent-through the electromagnet 25 once in every five revolutions of the exploring disc 12. When the electromagnet is excited, it attracts an armature attached to the arm 22 and exposes the appropriate light-sensitive cell. I Vhen the exploring disc 12 has completed one revolution, the current is cut oil from the electromagnet and switched on to the next one, thus covering up the light-sensitive device which was previously exposed, and exposing the next adjacent one. The commutator may either be driven by gearing from the exploring disc shaft or directly by a pawl-and-ratchet mechanism.

A convenient form of commutator is illustrated diagrammatically in Figure 6 and comprises a disc of insulating material fast upon a shaft 82 which is operatively connected with the exploring disc 12 so as to make one fifth of a revolution for each revolution of the exploring disc. The disc 80 carries a series of spirally-arranged contacts 84, 86, 88, 90, 92, all electrically connected together by conductors 94, and it carries also a contact ring 93 which is connected with the contact 92 by a conductor 96. A brush 98 bears upon the ring 93 and is connected by a conductor 100 with one pole of a battery 102, the other pole of which is connected to a conductor 104 which in turn is connected with one end of the winding of each of the electro-magnets 25 (Figure 4). The other end of each of the windings of the electromagnets 25 is respectively connected by one of five conductors 106, 108, 110, 112, 114, with one of five brushes 116, 118, 120, 122, 124, the tips of which brushes (their lower ends in the diagram) are situated respectively in the paths of movement of the contacts 84, 86, 88, 90, 92. Assuming that the disc 80 is rotating in the direction indicated by the arrow and, starting from the position shown in- F igure 6, it will be seen that the brush 116 will bear upon the contact 84 during one fifth of a rotation of the disc and that during such time current from the battery 102 will, through the connections described, energize the winding of the electro-magnet 25 that is connected to the brush 116, so that the'plate 21 (Figure 4) controlled by that electromagnet will be moved aside to uncover one of the light-sensitive devices, say the device 31. During the next one-fifth revolution of the disc 80, the brush 118 will engage the contact 86 and current will then flow from the battery 102 by way of the brush 118 and other connections described to the electromagnet which. controls the plate 21 of the next adjacent light-sensitive device, say 32, thus causing this plate to be moved to uncover such device. In a similar manner during continued rotation of the disc 80, the contacts 88, 90, 92 will come successively into engagement with the brushes 120, 122, 124:, each remaining in contact with its respective brush during one fifth of a revolution of the disc so that each of the three remaining light sensitive devices 33, 34, 35 will be uncovered in succession and remain uncovered during the corresponding time-period.-

I claim 1. In electro-optical apparatus for use in the production of images, the combination with a plurality of electro-optical elements, of scanning means associated with said elements, said scanning means having a maximum displacement suflicient to cover an area which is a portion only of a given field of vision as regards any one electro-optical element, said elements being so disposed that each is appropriated to a different portion of the field of vision by said scanning means, and means for rendering inoperative all but one of said elements at a given time.

2. In electro-optical apparatus for use in the production of images, the combination with a plurality of electro-optical elements, of scanning means associated with said elements, said scanning means having a maximum displacement suflicient to cover an area which is a portion only of a given field of vision as regards any one electro-optical element, said elements being so disposed that each is appropriated to a different portion of the field of vision by said scanning means, and opaque means interposed between said elements and said field of vision, said means having light transmitting portions for exposing said elements successively.

3. In electro-optical apparatus for use in the production of images, the combination with a plurality of electro-optical elements, of scanning means associated with said elements, said scanning means having a maximum displacement sufficient to cover an area which is a portion only of a given field of vision as regards any one electro-optical element, said elements being so disposed that each is appropriated to a different portion of the field of vision by said scanning means, and a 1'0- tating shutter interposed between said elements and said scanning means for exposing said elements one at a time.

4. In television apparatus, the combination with a plurality of light sensitive devices, of scanning means associated with said elements, said scanning means having a maximum displacement suflicient to cover an area which is a portion only of a given field of vision as regards any one electro-optical element, said devices being arranged so that each receives light from an area which comprises a portion only of the field of vision, and means for exposing said devices in succession and one at a time to the light.

5. In electro-optical apparatus for use in the production of images, the combination with a plurality of electro-optical elements, of scanning means associated with said elements, said scanning means having a maximum displacement sufficient to cover an area which is a portion only of a given field of vision as regards any one electro-optical element, said elements being so disposed that each is appropriated to a diiierent portion of the field of vision by said scanning means, means for rendering inoperative all but one of said elements at a given time, said last named means comprising a plurality of electro-magnetically operated devices, one associated with each light, and means for energizing said devices insuccession. v

In testimony whereof I aflix my signature.

JOHN LOGIE BAIRD. 

